That's because there is hardly any bubble this time. Last time it $10 to $260 in relatively short time period. Price should be at least at $500 before we can even began to talk about bubble.
I think this is not true...
We had a jump $140 to $200 in about 24 hours, and then another jump again $200 to $260 (and back to $60) in another 24 hours. It was definitely much slower in the weeks and months before that. Now we moved $155 to $195 in about 24 hours, that is definitely not normal growth. The only moments bitcoin had this growth EVER was during the bubbles. (excluding dead cat bounce after a massive crash)
If you compare side by side the April bubble with the current one, you can clearly see where we are. This speed of growth $140 to $200 is pretty much the same as the part of the previous bubble from $60 to $120. What happened next was a mad jump doubling again $120 to $240 in . If this is any similar we can see price skyrocket to over $300 or $350 in the next couple days, then badly crash, probably to $100 or so.
I suppose, if price is rising $200 to $250 in more than a week or so, then we are almost safe, and the bubble may touch $500 as you say, but that is when it burst, not when we "begin to talk about bubble", as we are just in the middle of one.
The only problem with this theory is that it is shared by many. And when a recent bubble is so clear in the investor and trader communities psyche, I wouldn't assume patterns will develop in such a predictable manner.
I suspect when the smoke clears this rally will not be compared to April 2013, at least in a way that is meaningful.